1. Field of the Invention
The invention relates to a metal mold apparatus which is used for forming a formed product having a desired shape and solidifying within a cavity, by filling a molten forming material such as a metal material, a resin material or the like in the cavity. The metal mold apparatus in which the cavity is formed by and comprises an insert fitted to an inner portion of a main mold.
2. Description of the Related Art
A metal mold apparatus of a related art as shown in Japanese Patent Application Laid-Open No. 2009-56503 has a fixed main mold 1 and a movable main mold 2, and has an insert 1A fitted to an inner portion of the fixed main mold 1, and an insert 2A fitted to an inner portion of the movable main mold 2, as shown in FIG. 5. A cavity 3 having a predetermined shape is formed in the inner portions by moving so as to close the movable main mold 2 with respect to the fixed main mold 1, and by mold closing the insert 1A of the fixed main mold 1 and the insert 2A of the movable main mold 2. A formed product P solidifying within the cavity 3 and having a desired shape is formed by filling a molten forming material in the cavity 3.
The metal mold apparatus is provided with a hole 4 in the insert 2A of the movable main mold 2, and receives a bush 5 for an extrusion pin into the hole 4. The hole 4 is constructed by a larger diameter hole portion 4A on an opposite side to a cavity forming surface 3A, and a smaller diameter hole portion 4B on a side of the cavity forming surface 3A. A larger diameter portion 5A of the extrusion pin bush 5 is inserted into the larger diameter hole portion 4A from a back face side of the insert 2A (an opposed side to the cavity forming surface 3A), and a smaller diameter portion 5B is inserted into the smaller diameter hole portion 4B. When the insert 2A to which the extrusion pin bush 5 is inserted is fitted to the inner portion of the movable main mold 2, the extrusion pin bush 5 is sandwiched particularly regarding its larger diameter portion 5A by the inner surface of the movable main mold 2 and the larger diameter hole portion 4A of the insert 2A so as to be solidified.
Further, in the metal mold apparatus, the movable main mold 2 is provided with a hole 6 which passes through coaxially and with the same inner diameter from an outer portion of the movable main mold 2 toward an inner diameter portion 5C of the extrusion pin bush 5, in a state in which the insert 2A inserting the extrusion pin bush 5 thereto is fitted to the inner portion of the movable main mold 2. Further, an extrusion pin 7 is inserted into the inner diameter portion 5C of the extrusion pin bush 5 from the outer portion of the movable main mold 2 via the hole 6 of the movable main mold 2. Each of insertion end surfaces of the extrusion pin bush 5 and the extrusion pin 7 to the smaller diameter hole portion 4B and the inner diameter portion 5C is arranged on the same surface as the cavity forming surface 3A of the insert 2A. An extrusion plate 8 is provided on a base end portion which protrudes to the outer portion of the movable main mold 2 in the extrusion pin 7.
Accordingly, the mold is opened by moving so as to open the movable main mold 2 from the fixed main mold 1, at a time when the formed product P is formed within the cavity 3 of the fixed main mold 1 and the movable main mold 2. At this time, the formed product P is released from the insert 1A of the fixed main mold 1, and is attached to the insert 2A of the movable main mold 2. Thereafter, the formed product P is released from the insert 2A of the movable main mold 2 so as to be detached, by protruding the extrusion pin 7 into the cavity 3 of the insert 2A by using the extrusion plate 8.
In the conventional metal mold apparatus, there is a case that actuations of the extrusion pin 7 and the extrusion pin bush 5 are deteriorated by repeatedly using the extrusion pin 7, and the extrusion pin 7 is broken. At this time, since the extrusion pin 7 and the extrusion pin bush 5 are gnawed, the extrusion pin 7 can not be drawn out of a side of the extrusion plate 8. It is necessary to draw out the extrusion pin 7 from the insert 2A of the movable main mold 2 together with the extrusion pin bush 5 in accordance with the following procedure.
(1) bring down the movable main mold 2 from a casting apparatus.
(2) detach the extrusion plate 8.
(3) detach the insert 2A from the movable main mold 2.
(4) detach the extrusion pin bush 5 and the broken extrusion pin 7 from a back face side of the insert 2A (an opposed side to the cavity forming surface 3A).
(5) insert a new extrusion pin bush 5 to the hole 4 of the insert 2A from the back face side of the insert 2A.
(6) reassemble the insert 2A to the movable main mold 2.
(7) insert a new extrusion pin 7 to the hole 6 of the movable main mold 2 and the inner diameter portion 5C of the extrusion pin bush 5 from the outer portion of the movable main mold 2. Attach the extrusion plate 8 to the extrusion pin 7.
(8) return the movable main mold 2 to the casting apparatus.
In the related art, it is necessary to detach the insert 2A from the movable main mold 2 and thereafter reassemble (detach and attach), for replacing the broken extrusion pin 7. Man hours for replacing is increased. Particularly, the movable main mold 2 and the insert 2A have a tight fit, and are hard to be detached and attached.